This fibrinogen-derived inhibitory peptide attenuates microglia activation and suppresses relapsing paralysis in multiple sclerosis (MS). Fibrinogen is a regulator of microglia activation and interaction of fibrinogen with the microglia integrin receptor Mac-1. Because blocking fibrinogen–Mac-1 interactions affects the pro-inflammatory but not the pro-coagulant properties of fibrinogen, targeting this gamma- fibrinogen epitope could represent a potential therapeutic strategy for MS and other neuroinflammatory diseases associated with blood-brain barrier disruption and microglia activation.